The objective of this study is to examine the impact of various material and processing factors on the hardness (Shore D) and tensile strength of PLA/graphene composites. The study employed the Taguchi method to systematically optimize and statistically analyze various process variables, including the content of graphene (0 %, 0.5 %, and 1.0 % by weight), infill density (80 %, 90 %, and 100 %), and print speed (160 mm/s, 170 mm/s, and 180 mm/s). The composite material was fabricated utilizing the fused filament fabrication (FFF) technique, employing polylactic acid (PLA) and graphene as the primary feedstock materials. A standardized experiment was conducted in accordance with ASTM standards to assess the hardness and strength of samples that were prepared based on the experimental design. Based on the S/N ratio response table, it can be concluded that the reinforcement content is the most significant factor affecting both hardness and tensile strength. The optimal combination of process variables for achieving high hardness and tensile strength was found to be a graphene content of 1 %, an infill density of 100 %, and a print speed of 180 mm/s. The analysis of variance (ANOVA) indicated that the variable with the greatest statistical significance and substantial impact on the properties is the content of reinforcement. The analysis of fractures indicated a transition from ductile to brittle behavior with an increase in infill density. Furthermore, both composites demonstrated a brittle mode of failure irrespective of the infill density. Thus this composite material synergistically combines the inherent biodegradability of PLA with the improved thermal conductivity of graphene. © 2024 Elsevier B.V., All rights reserved.